atcomsystems.ca/forum Forums General General Telephone & Systems Information Phone ok - Fax doesn't work - hear radio

I don't think inductive noise (radio) would make anything think there was an off hook. Most of this type of interference comes from the IW acting as an antenna. If nothing else take the fax to a friends and see if it works, if it does look for something physical on the IW, which you should be able to hear on a termination if there is, or a high resistance short, which should cause static or cutouts.

it thinks that the line is being used/off the hook (I guess because of the radio transmission/line noise).

Nahh, no way. One side of the line is open if you can't draw dial tone when the fax goes off hook. The imbalance is what causes the RF pickup. Look at the facts:

1) Machine suddenly stopped working.
2) New machine does not work either.

Unless they put a new transmitter on the air at the same time the fax machine stopped working your RF interference theory doesn't wash, if it ever did. It is normal for an unterminated line to pick up radio stations if the RF is strong enough. I get it at some locations with my butt set on monitor and even my toner probe. Go off hook and the radio station disappears and you get dial tone.

I assume you say that you plugged a phone into the jack and it worked? Then I would take a good look at the jack itself (probably replace it) as well as the line cord going to the fax. Has to be there.

-Hal

Ok - first, thanks for all the replies. All is working fine, here's what I did. I replaced the jack because I noticed upon removal that it wasn't flush with the faceplate (looked as if it had been hit with something). I have a couple of office chairs with wheels (home office) and kids that love to roll around on them....so, perhaps... This did not give me dialtone, but did seem to get rid of the interference. I was also researching and came across a tech doc that mentioned some fax machines require a two conductor phone cable instead of a four conductor cable. I changed out the cable and now have dialtone. Never would have thought this would be an issue.

Thanks Hbiss and everyone else who replied - if you guys could have seen it, it would probably have been a no-brainer for you all. I appreciate your patience for an amateur troubleshooter.

[This message has been edited by tpiercelackey (edited April 22, 2005).]

[This message has been edited by tpiercelackey (edited April 22, 2005).]

just fyi it should have worked just as good with the 4wire cord. i suspect your 4wire cord was open one side causing an unbalance allowing it to work as an antenna. and when you repld it with the 2wire you simply cured the open especially if your phone was working fine. the only time that i have seen a trouble out of the second pr in a cord was when the jack was wired alead control or once upon a time wired for a second line. ps if you were to monitor the ckt with a butt set on hook you would probably hear your radio station.

a tech doc that mentioned some fax machines require a two conductor phone cable instead of a four conductor cable.

Anything of recent vintage that uses a 2 wire cord won't have anything connected to the other pins on the line jack so this makes no sense.

I remember many years ago there were answering machines that had A-lead control on pins 3&5 for when they were used behind 1A2 systems. You had to be careful (or at least use a 2 wire line cord) if you used them behind a key system that had power on pins 3&5.

-Hal

I wouldn't have believed the cable would matter either, but here's the link to the tech doc: https://h10025.www1.hp.com/ewfrf/wc/genericDocument?lc=en&cc=us&docname=c00014834
I looked at the jack and cables (I'm not of the level of you guys) and for the life of me could not figure out why the cable would matter. I then justifiably cursed HP for my troubles caused by their design (and my ineptness) and faxed the docs that had stacked up.

HP doesnt say how or why it would effect service. What we can surmise is that if it is not pinned out in the fax machine because of penny additional cost and most of the time it is not . Even though the second pr (o/w or y/bk) need not be used, it is usually terminated thus adding the possibility of acting as an influence to rfi or emf/emi. In my experience i just havent seen five foot of cord generating a trouble as your describing. But i do find this basic trouble interesting. Try the cord in another telephone to see it is any good. Then do as i do and cut it in half so there is no chance of reuse. Ill still put my money on a bad cord or poorly seated plug/jack.

Probably they are taking all circumstances into account and no saying what they may be.

Only thing that I can think of is if you are using a two line jack. It is possible that with the second line on the outer pair of the line cord there could be a crosstalk issue (either the fax interfering with the second line or vice versa) because these are not twisted pairs. Had this plenty of times with runs of old 4 wire station wire that is used for two lines. Not something that will usually cause the fax not to operate though I have heard of a case where crosstalk of the CNG tone caused a fax on another line to go into receive.

-Hal

Just a quick test:

Hook up a standard phone to the jack. Go "off hook". Assuming that you have dial tone, dial a couple digits to break dial tone. Do you hear dead silence, or "radio"? If you don't hear "radio", then your fax/modem/other won't either, unless the equipment has issues. If you do hear "radio", then change the line cord and try again. If you still hear "radio", do the same test at the d-mark (point of entry for non-techies ). If you still hear "radio", then the trouble is on the service providers wire.

If the fax machine has a built in handset, then do the same test with just the fax machine at the jack.

This should help you narrow down the possibilities. Hope it helps.